1. The Field of the Invention
The present invention relates to methods and apparatus for delivering dental agents to tooth surfaces. More particularly, the present invention is ideally suited for applying a highly filled, thixotropic sealant to tooth surfaces in a manner which minimizes polymerization shrinkage and water absorption, and which provides for a stronger and more durable sealant so as to more effectively prevent tooth decay.
2. The Prior Art
Most dentists understand the value of using sealants as a prophylactic measure with emerging dentition. Sealants have proven to be an important adjunct to patient care. However, many clinicians avoid the usage of sealants due to products which fail to produce predictable, consistent results. This is due in significant measure to two factors. First, low-filled or unfilled resins have been the materials of choice to date, since low viscosity is necessary to maximize resin penetration into fissures. However, the problems with using low-filled or unfilled resins include shrinkage, increased water absorption, less strength, and less durability of the sealant.
On the other hand, to date, utilization of highly filled resin sealants e.g., those which contain approximately fifty percent (50%) filler has not been practical because the filler makes delivery using conventional delivery tips virtually impossible due to the high viscosity. For example, my prior U.S. Pat. No. 4,997,371, discloses a syringe-type dispenser with a removable applicator tip having bristles at the distal end thereof. The bristles are in communication with the syringe-type dispenser, thereby allowing a dental agent to be continuously applied to tooth surfaces without the need to stop the dental procedure and rewet the applicator. This device has proven to be highly effective with respect to the delivery of a number of different kinds of dental agents.
On the other hand, attempts to use this device for delivery of other dental agents that are more viscous or which are constituted of highly filled resins have proven unsatisfactory. For example, the bristles which are held by the applicator tip are primarily held by the frictional grip which occurs at the distal end of the tip. This causes the bristles to act as a filter, particularly with respect to any filler particles that are contained in the dental agent. Such filtering may change the physical properties of the dental agent as it is delivered to the tooth surface. For example, in the case of a bonding agent, filtering of the filler particles may make the actual bond weaker. Sometimes, such filtering can even tend to choke off the delivery tip, thus preventing flow of material. With some types of materials, such as highly filled sealants, it is virtually impossible to deliver the dental agent since the resistance to flow is simply too great and attempting to force the flow of the material through the applicator tip may actually cause the tip to be blown off, expelling undesired quantities of the material into the patient's mouth.
Accordingly, while it would be highly desirable to provide sealants which are highly filled (e.g., containing approximately fifty percent (50%) filler) so as to provide a sealant capable of greatly minimizing polymerization shrinkage and water absorption, while increasing strength and durability, to date there have not been adequate methods or apparatus available for accomplishing this result.